Question

在详细视图控制器中，用户可以将字符添加到收藏夹列表中。单击“收藏夹”按钮会将图像URL添加到CoreData。然后在集合视图控制器中，我运行以下代码：

override func viewDidLoad() {
    super.viewDidLoad()
    let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
    let request = NSFetchRequest<NSFetchRequestResult>(entityName: "Favorite")

    request.returnsObjectsAsFaults = false

    do {
        let results = try context.fetch(request)
        if results.count > 0
        {
            for result in results as! [NSManagedObject]
            {
                if let favFig = result.value(forKey: "favFig") as? String
                {
                    favFigArray.append(favFig)
                }
                if let favFigID = result.value(forKey: "favoriteID") as? String
                {
                    favFigIDArray.append(favFigID)
                }
            }

        }
    } catch {
        print("Error Fetching")
    }
}

favFigArray然后包含图片网址列表。要将图像设置为我的集合视图单元格，我使用以下代码：

func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "ownedCell", for: indexPath) as! OwnedCollectionViewCell
    cell.ownedFigImage.sd_setImage(with: URL(string: favFigArray[indexPath.row]))

    return cell
}

我遇到的问题是，当用户想要返回详细视图控制器并向收藏夹列表添加更多字符时，集合视图将不会更新。我尝试在viewWillAppear中使用self.ownedCollectionView.reloadData（），但这不起作用。 CoreData正在正确更新，但favFigArray未更新。

任何人都可以帮我重新加载吗？谢谢！

Answer 1

您可以创建一种过滤结果的方法，如下所示

func filterFavFigData()
     favFigArray.removeAll()

     let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
     let request = NSFetchRequest<NSFetchRequestResult>(entityName: "Favorite")

     request.returnsObjectsAsFaults = false

     do {
        let results = try context.fetch(request)
        if results.count > 0
        {
            for result in results as! [NSManagedObject]
            {
                if let favFig = result.value(forKey: "favFig") as? String
                {
                    favFigArray.append(favFig)
                }
                if let favFigID = result.value(forKey: "favoriteID") as? String
                {
                    favFigIDArray.append(favFigID)
                }
            }
        }
    } catch {
        print("Error Fetching")
    }
}

然后更新您的viewWillAppear，如下所示

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)
    self.filterFavFigData()
    self.ownedCollectionView.reloadData()
}

无法重新加载收藏查看Swift 4

1 个答案: